Axial flow compressor apparatus



April 22, 1958 M. J. BRUNNER 2, I AXIAL FLOW COMPRESSOR APPARATUS Filed Jan. 15, 1954 2 Sheets-Sheet 1 mmw hm Umm 0m mum @mm mm www INVENTOR IMATHIAS J.BRUNNER BY Q i 9 [Q ATTORNEY April 22, 1958 M. J. BRUNNER 2,831,627

AXIAL FLOW COMPRESSOR APPARATUS Filed Jan. 15, 1954 2 Sheets-Sheet 2 no I54 I3! '30 H8 E 14s m HIHHIF L9 2 Ius1 F 0.

|oo m 11 1 FIGS 5 INVENTOR 3 MATHIAS J. BRUNNER u m BY O I l I I I v *rv .YM

I I 2 5 4 5 s 7 a 9 IO PRESSURE RATIO ATTORNEY United States Patent AXIAL FLOW COMPRESSOR APPARATUS Mathias I. Brunner, Broomall, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 15, 1954, Serial No. 404,292

4 Claims. (Cl. 230-114) This invention relates to axial flow compressors, more particularly to multi-stage, axial flow compressors for providing air or other gaseous fluids under pressure, and has for an object to provide a compressor of the above type having improved performance characteristics under various operating conditions.

in many applications, a multi-stage compressor operating under substantially constant inlet flow and rotational speed conditions is required to perform under various air outlet to air inlet pressure ratio conditions, including low pressure ratio conditions as well as the high pressure ratio conditions for which the compressor is designed. However, most conventional multi-stage compressors of the above type perform at peak efiiciency only under high pressure ratio conditions, their efi'iciency decreasing to a low value under low pressure ratio conditions.

In view of the above, it is a further object of the invention to provide a multi-stage, axial flow compressor of the above type operable at high efficiency under various air outlet to air inlet pressure ratio conditions, including high pressure ratio conditions and low pressureratio conditions.

it is another object of the invention to provide a multistage axial flow compressor of the above type which is compact in design, requires a minimum of space for installation and lends itself to economies in cost of manufacture.

In accordance with the invention, there is provided an axial flow compressor having a plurality of multi-stage air compressing sections. Each of the sections is provided with a bladed rotor and the usual complementary stationary blading. The rotors are connected in tandem by individually disconnectible coupling mechanisms, so that one or more sections may be utilized to compress the air as required by the air outlet to air inlet pressure ratio condition to be maintained. A continuous air passage extending from the downstream end of the low pressure section to the discharge outlet of the compressor is provided with a plurality of valves operable to divert the pressurized air around the sections in which the rotors are disconnected, thereby preventing windmilling of the disconnected rotors and eliminating attendant operating losses.

The above and the objects are attained by the invention as will be apparent from the following description taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a schematic longitudinal vertical sectional view of a wind tunnel compressor incorporating the invention, the compressor being illustrated in operative condition for maximum pressure ratio performance;

Fig. 2 is a further simplified schematic view of the compressor taken on a smaller scale and showing the compressor in operative condition for intermediate pressure ratio performance;

Fig. 3 is a schematic viewsimilar to Fig. 2, but showing the compressor in operative condition for low pressure ratio performance;

2 Fig. 4 is a greatly enlarged fragmentary sectional view taken on line IVIV of Fig. 1;

Fig. 5 is an enlarged "axial sectional view ofone of the disconnectible coupling mechanisms;

Fig. 6 is a fragmentary schematic view showing another embodiment of the invention;

Fig. 7 is a fragmentary schematic view similar to Fig. 6, but showing the compressor in another operative condition; and 1 Fig. 8 is a chart showing representative efiiciency curves attained with the invention.

Referring to the drawings in detail,espe,cially,Fig. 1,'

the invention is embodied in a multi-stage axial flow compressor 10 of the type utilized to provide pressurized air to a wind tunnel or .the like (not shown). The com pressor is provided with a plurality of multi-stage air compressing sections, namely, a low pressure section 11,

intermediate pressure sections 12 and 13, and a high pressure section 14, disposed in axial, alignment with each other within a tubular shell structure 15. The compressing sections 11, 12, 13 and 14 are provided with multi-stage bladed rotors 11a, 12a,'13a and 14a and complementary bladed stators 11b, 12b, 13b and fairing member 20 is mounted at the air outlet end 17;

Also, stationary core members 21, 22 and 23 are axially interposed between the air compressing sections 11,- 12, 13 and 14 respectively.

The rotors 11a, 12a, 13a and 14a are provided with shafts 22a, 23a, 24a and 25a, respectively, connected in tandem with each other. The rotor 11a is connected at the left end, to a source of substantially fixed angular velocity, by a-fiange 23b-provided on its shaft 22a. permanently coupled to each other by complementary flanges carried on the shafts 23a and 24a. The rotor 12a is connected to rotor 11a by means of a remotely controlled disconnectible coupling mechanism 26. Sim-- ilarly, the rotor 13a is connected to rotor 14a by a secanism 27.

As thus far described, the compressor operates in the following manner. When the rotor 11a is connected to the source of power, air enters the air inlet end 16 and is driven through the air compressing sections 11, 12, 13 and 14, traversing the primary passage 18 andbeing progressively increased in pressure before being discharged through the outlet end 17. Obviously, with all of the compressing sections connected to each other, the pressure ratio of the air at the outlet end to the air at the inlet end attains a maximum value.

In accordance with the invention, a secondary compressor shell member 30 encompassing'the main shell 15 and extending from a zone immediately downstream of the compressing section '11 to the air outlet 17 provides a secondary air passage 31 of annular shape. The secondary shell 30 is provided with front and rear frusto-conical portions 32 and 32a, respectively, which extend inwardly and are joined to the shell '15 and the outlet member 17. Axially spaced annular openings 33 and 34 are provided in the shell 15 for permitting-communication between the primary passage 18 and the secondary passage 31, and a third annular opening 35 is provided in the outlet member 17 for permitting communication between the secondary passage and the discharge outlet.

vA valve mechanism generally indicated 36 is provided power (not shown) having The rotors 12a and 13a are 3 for covering and uncovering the opening 33. The valve mechanism 36 may be of the iris type provided with an annular array of leaves 37 hinged at one end and disposed in overlapping relation to each other, as shown in Fig. 4. Each of'the leaves 37 may be independently actuated by separate hydraulic actuators 38 of the well known piston and cylinder type. The. hydraulic actuators 38 may be anchored to the shell 30 in any desired manner and may be connectedto the leaves 37 by means ofpivoted links.

As shown in Fig.- 1, the valve mechanism 36 is disposed in covering relation with the opening 33 and by actuation of the hydraulic actuators 38, the-leaves 37 maybe moved radially inwardlyto uncover the opening 33 and block the central passage 18 as indicated by the dotted lines 39a;

A second valve mechanism 40, generally similar to the valve mechanism 36 described above, is provided at the outlet end -17 for covering and uncovering the opening 35. In this instance, the leaves 37 are shown in covering relation with the opening 35 and are movable radially outwardly about hinge pins 41 to uncover the opening 35, the retracted position being indicated by the dotted lines 41 1.

. A third valve mechanism 43 of the iris type, similar tothe valve mechanism, 36 and operableby a separate set of hydraulic actuators 38, is provided intermediate the sections 13 and 14. The leaves 37 of the valve mechanism 43-arehinged at 44 and, as shown, are in covering-relation with the opening 34. Upon actuation by the hydraulic actuators 38, the leaves 37 may be swung radial- 1y outwardly to the dotted position 45a, thereby uncovering the annular opening 34 andblocking the secondary passage 31 immediately upstream of the opening 34.

-A' fourth valve mechanism 46, also similar to the valve mechanism 36, is provided for controllingthat portion of the primary passage 18 extending through the section 14. -As shown in Fig. l, the leaves 37 are disposed in a position in which the passage 18 through section 14 is open However, the leaves 37 may be swung radiallyoutwardly about hinge pins 47 to the dotted position 48a thereby blocking the primary passage at section 14 and diverting air flow through the opening 34 into the secondary passage 31. Y

As will be later described, the valve mechanisms 36, 40, 43 and 46 may be operated in various combinations to direct air flow through the compressor by various routes involving the'primary passage 18 and the secondary passage 31.

The coupling mechanism 26 may be of any desired type, for example, the hydraulically actuated type shown in Fig. 5.; comprising opposed spaced flange members 49 and 50 connected to the shafts 22a and 2311, respectively. Each of the flanges 49 and 58 has ring gear members 52 and 53, respectively, firmly imbedded therein. The flanges 49 and 50 are rotatably supportedwithin a liquid-tight housing 54 rotatably supporting the shafts 22a and 23a and supported in the shell by means of struts 55 and 56. The flange 50 is provided with a central bore or cylinder 57 within which is disposed a piston 58 having a shaft 59 extending axially therefrom in the direction of the flange 49. A gear member 60 of about the same pitch diameter as those of the ring gears 52 and 53 is rigidly attached to the end of the shaft 59 and is provided with a relatively wide tooth face 61 axially slidable into and out of engagement with the ring gear 52, although always maintamed in engagement with the ring gear 53. Thus, when the gear 60 is in the position shown in Fig. 5, the flanges 49 and 50 are connected to each other by the gear 60 and the shaft 22a is drivingly connected to the shaft 23a. The shaft 23:: has a pair of orifices 62 and 63 communicating wlth the cylinder 57 at opposite sides of the piston 58. Each of the orifices is in registry with annular ports 64 and 65 which, in turn, are connected'to hydraulic lines 67 and 68, respectively, so that, regardless of the angular position of the shaft 23a, the orifices 62 and 63 are always in registry with the ports 64 and 65.

To engage the coupling members 49 and 50, hydraulic fluid is admitted through the line 67 and orifice 62 into the right side of the cylinder 57, thereby moving the gear 60 to the left into engagement with the ring gear 52. When it is desired to disconnect the coupling members 49 and 541, hydraulic fluid is admitted through the line 68 and orifice 63 to the left-hand side of the cylinder 57 and exhausted from the right-hand side of the cylinder, thereby moving the gear 60 to the right and out of engagernent with the ring gear 52.

The coupling mechanism 27 may be identical to the coupling mechanism 26 described above, the only difiiercase being that it serves to connect shaft 24a to shaft 250. Hence, it needs no further description.

Operation When it is desired to operate the compressor under maximum outlet to inlet pressure ratio conditions, the compressing sections 11, 12, 13 and 14 are connected to each other by means of the disconnectible couplings 26 and 27. Thus, with power of constant angular velocity, the air drawn through the inlet 16 is progressively compressed by the compressing sections 11, 12,13 and 14 as it flows through the primary passage 18 to the discharge outlet 17, as shown in Fig. 1.

When it is desired to operate the compressor under intermediate outlet to inletpressure ratio conditions, as indicated in Fig. 2, the coupling 26 is-retained in the engaged position while the coupling 27 is actuated to the disengaged position. Under these-conditions, the compressing section 11 is drivingly connected to the compressor sections 12 and 13, while the compressor section 14 is disconnected. Also, the valve mechanism 36 is retained in the position in which the leaves 37 are disposed in their maximum radially outward position and cover the opening 33. The valve mechanism 43 is actuated so that its leaves 37 are disposed in their maximum radially outward position, blocking the secondary passage 31 and uncovering opening 34, while the valve mechanism 46 is actuated so that its leaves 37 are in their maximum radially outward position, blocking the primary passage 18 through the compressing section 14. The valve mechanism 40 is actuated to the position in which its leaves 37 are in their maximum radially outward position in which the opening 35 is uncovered. With the valves disposed in the positions mentioned above, air is drawn into the inlet 16, through the compressing sections 11, 12 and 13 by way of the primary passage 18 and is then deflected radially outwardly through the secondary passage 31 to the discharge outlet 17. With this arrangement, the air attains a pressure which is proportionately less than when all of the compressing sections are in driving relation therewith. It will be noted that the leaves of the valves 36, 43, 46 and 40 are so positioned that the air in passing through the compressor from inlet to outlet flows through a smoothly contoured route and does not encounter abruptly deflecting surfaces. Also, it will be noted that when the compressing section 14 is out of the compressing circuit, the air flow is directed about the compressing section 14, so that the rotor 14:: thereof is not subjected to wind milling.

When it is desired to operate the compressor under low air outlet pressure to air inlet pressure ratio conditions, as indicated in Fig. 3, the coupling 26 is actuated to disconnect the shaft 23a from shaft 22a of the compressing section 11, thereby rendering the compressing sections 12, 13 and 14 inoperative, so that the air is compressed by the compressing section 11 alone. The valve mechanism 36 is actuated to the position in which the opening 33' is uncovered and the central passage 18 is blocked in the zone intermediate the compressing sections 11 and 12. Also, the valve mechanism 40 is retained in the position in which the opening 35 is uncovered, while the valve mechanism 43 is actuated to cover the opening 34. Since the primary passage 18 downstream of the rotors 12 and 13 is out of the air flow circuit, the valve mechanism 46 may be left in the positionshown in Fig. 2 or may be actuated to the position shown in Fig. 3. It will now be seen that air entering the inlet 16 passes through the compressing section 11, through the primary passage 18, and is then diverted radially outwardly by the valve mechanism 36, through the secondary passage 31, and is finally admitted to the discharge outlet 17 through the opening 35. Here again, it will be noted that the flow of the air passing through the compressor follows a smooth path and that the rotors 12a, 13a and 14a, which are in the inactive state, are bypassed by the air flow so that windmilling of these rotors is eliminated.

In Fig. 8 there is shown a chart illustrating the efficiency characteristics of the compressor under various pressure ratios. The efficiency and pressure ratio values are shown for a typical compressor incorporating the invention. Curve I illustrates the efiiciency of the compressor when all of the compressing sections are connected together to pressurize the air to maximum pressure ratio values. Curve H illustrates the efiiciency curve when sections 11, 12 and '13 are connected together for pressurizing the air to an intermediate pressure ratio value, while curve III illustrates the efliciency of the compressor when the compressing section 11 is operated alone to pressurize the air to a low pressure ratio value.

From an inspection of the above curves I, II and HI, it will be noted that with the invention disclosed herein the compressor may be operated at approximately peak efiiciencies for any pressure ratio within the limits of operation. The locations of the maximum efliciency peaks of the curves are determined by the particular design of the compressor and the number of sections connected in driven relation with the power supply. It will also be noted from further inspection of curve Ithat, when all of the compressing sections are utilized to provide pressurized air of various pressure ratios including the intermediate pressure ratios and the low pressure ratios, the efliciency of the compressor falls rapidly proportionately to the pressure ratio of the air outlet to the air inlet.

Although not specifically shown and described, the valve mechanisms 36, 4t), 43 and 46 may. be operated in unison or in succession and may be positioned before power is applied to the rotor 11a. Also, the couplings 26 and '27 may be actuated conjointly with or separately from the valve mechanisms. In the embodiment shown, the couplings 26 and 27 are actuated while the rotor is stationary.

-Although one particular valving arrangement has been shown and described in connection with Figs. 1 through 5, other valve arrangements for diverting the flow through the various air passages in the compressor may be utilized in accordance with the invention.

The fragmentary schematic sectional views shown in Figs. 6 and 7 illustrate the invention incorporated in a compressor 110 which is generally similar to the compressor 10 heretofore shown and described and diifers therefrom only in the arrangement of the iris valves. It is to be understood that those portions of the compressor not illustrated in these views may be the same as in the first embodiment.

Referring to Figs. 6 and 7 in detail, the compressor 110 has an intermediate air compressing section 113 and a high pressure section 114 provided with rotors 113a and 114a, respectively, connected to each other in tandem by a coupling mechanism 127. The rotors 113a and 114a are disposed within a main tubular shell 115 and together therewith define a primary air passage 118 of annular sha e.

r? secondary shell 130 surrounds the main shell 115 and provides a secondary air passage 131. It will be understood that the primary passage 118 and the secondary passage 131 extend inupstream direction, in a manner similar to that described in the first embodiment, to a zone immediately downstreamof the low pressure section (not shown in this embodiment). The secondary shell extends downstream beyond the high pressure section 114 and an outlet opening of annular shape is provided connecting the secondary passage 131 with the outlet end portion 117 of'the compressor. The primary passage 118 also has its outlet in communication with the outlet end portion 117.

An annular opening 134 is provided in the main shell 115 in a zone intermediate the compressing sections 113 v and 114. An iris valve mechanism 146 is arranged in such a manner that when moved by the hydraulic actuator 38 to the outwardly extended position shown in Fig. '6, the annular opening 134 is blockedandthe primarypassage 118 is unblocked, while when moved to theinward position shown in Fig. 7, the opening 135 is unblocked and the primary air passage 118 is to the compressing section 114;

It will now be seen that when the valve mechanism 146 is in the position shown in Fig. 6 and the rotor 114a is connected to the rotor 113a by the coupling 127, the

pressurized air flowing downstream through theisection- 113 in the primary passage 118 is delivered to the section 114 whereit is further pressurized before being delivered to the outlet of the compressor.

Referring to Fig. 7, when the valve 146 is in the-posh. tion shown therein, and the rotor 11411 is uncoupled from the rotor 113a the pressurized air passing through the section 113 is diverted through the opening 134 into the secondary passage 131, and delivered to the outlet it? through the opening 135. Thus, it will'be seen that when the section 114 is in deactivated condition, the pressurized air is diverted about it to the outlet, thereby avoiding the Windmilling action of the rotor114-as previously described.

With this arrangement, the valve mechanism 40 and i the valve mechanism 37, utilized in the first embodiment, are eliminated, thereby simplifying the design and manufactnre of the compressor and providing economies in the manufacture.

It will now be seen that the invention provides a compressor which is adaptable to various pressure ratio requirements and operable at substantiallyhigh eflicienci'es throughout its operating .range. It will further be noted that the control is readily etfected by power actuated remotely controlledapparatus.

The invention may be readily applied .to compressors having more or less air compressing sections than those shown in the illustrated embodiment.

Also, although a compressor of large physical dimensions suitable for wind tunnel installations has been shown for illustrative purposes, the invention may be readily applied to compressors of considerably smaller size suitable for other applications, without departing from the spirit or scope of the invention.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof. i

What is claimed is:

1. In a multi-stage axial flow air compressor, a tubular shell, a plurality of bladed rotors disposed in said shell and together therewith defining a main annular air passage, said rotors including first and second rotors for providing low and high pressure sections, respectively, for the dew of air axially through said annular air passage, said rotors being disposed in tandem with each other, coupling means between said first and second rotors for selectively interconnecting and disconnecting the same, means for connecting said first rotor to a source of power, whereby said second rotor is driven only when connected blocked at the inlet to said first rotor by said coupling means, means providing a secondary air passage in bypass relation with said annular passage around said second rotor, said secondary passage means having'an opening communicating with said annular passage at a zone intermediate said first and second rotors, and means including a valve selectively movable to first and second positions, said valve covering said opening in said first position, and said valve blocking said annular passage at said zone and uncovering said opening in said second position.

' 2. In an axial flow air compressor, a plurality of multistage air compressing sections, each of said sections comprising-a bladed rotor and complementary bladed stators, said rotors being disposed in tandem with each other, tubular means encompassing said rotors and stators and together therewith defining a primary annular air passageysaidfrotors including first and second rotors, couplingmeans between said first and second rotors for selectively interconnecting and'disconnecting the same, means for connecting said first rotor to a source of power, whereby said first rotor is in driving relation with said secondrotor, means including a tubular shell providing a secondary annular air passage in bypass relation with the portion of said primary air passage extending through said second rotor, said secondary passage means having an annular opening communicating with said primary passage at a zone intermediate said firstjand; second rotors, and means for diverting air flow through-said-secondary passage including a valve selectively movable to first and second positions, said valve covering said annular opening insaid first position, and said valve blocking'said primary passage at said zone and uncovering said annular opening in said second position.

- 3.- In a multi-stage axial flow air compressor, a tubular shell, a plurality of bladed rotors disposed in said shell and together therewith defining a main annular air passage, said rotors including first and second rotors for providing low and high pressure sections, respectively, for-the flow of air axially through said annular air passage, said rotors being disposed in tandem with each other, coupling means between said first and second rotors for selectively interconnecting and disconnecting the same, means for connecting said first rotor to a source of power, whereby said second rotor is driven only when connected to said first rotor by said coupling means, means including a tubular member encompassing said tubular shell and providing a secondary air passage of annular shape in bypass relation with said main annular passage around said second rotor, said secondary passage means having an annular opening communicating with said main annularl passage at a zone intermediate said first and second rotors, and means including a valve selectively movable to first and second positions, said valve covering said opening in said first position, mid said valve blocking said main passage at said zone and uncovering said opening in said second position, said valve comprising an annular array of movable leaf members disposed in overlapping relation to each other.

4. In an axial flow air compressor, a plurality of multistage air compressing sections, each of said sections comprising a bladed rotor and complementary bladed stators, said rotors being disposed in tandem with each other, tubular means encompassing said rotors and stators and together therewith defining a primary annular air passage, said rotors including first and second rotors, coupling means between said first and second rotors for selectively interconnecting and disconnecting the same, means for connecting said first rotor to a source of power, whereby said first rotor is in driving relation with said second rotor, means including a tubular shell providing a secondary annular air passage in bypass relation with the portion of said primary air passage extending through said second rotor, said secondary passage means having an annular opening communicating with said primary passage at a zone intermediate said first and second rotors, means for diverting air flow through said secondary passage' including a valve selectively movable to first and second positions, said valve covering said annular opening in said first position, and said valve blocking said primary passage at said zone and uncovering said annular opening in said second position, a member defining a main outlet passage communicating with said primary passage, said secondary passage means extending to said main outlet passage member and having a second opening communicating with said main outlet passage, and second valve means for selectively covering and uncovering said second opening.

References Cited in the file of this patent UNITED STATES PATENTS 

